1. Field of the Invention
The present invention relates to devices and methods used to obtain radiography images, and to such devices in which a detector and a radiation source are in communication with a computer regarding orientation and location of the detector and the radiation source.
2. Description of Related Art
Modern medical facilities such as hospitals or emergency care facilities are often large and complex organizations. A medical facility may be organized into various departments or branches that specialize in a particular type of patient care or expertise. For example, a medical facility may have a radiology department that handles various medical imaging tasks such as computed tomography (CT) systems, X-ray systems (including both conventional and digital or digitized imaging systems), magnetic resonance imaging (MRI) systems, positron emission tomography (PET) systems, ultrasound systems, nuclear medicine systems, and the like. Such systems provide invaluable tools for identifying, diagnosing and treating physical conditions and greatly reduce the need for surgical diagnostic intervention. In many instances, these modalities complement one another and offer the physician a range of techniques for imaging particular types of tissue, organs, physiological systems, and so forth. However, patients requiring an X-ray, for example, must often be transported to the radiology department or even a separate and geographically distant imaging center. This can present additional delays, costs, and inconveniences to the patient and the practitioners.
Digital imaging systems are becoming increasingly widespread for producing digital data that can be reconstructed into useful radiographic images. In one application of a digital imaging system, radiation from a source is directed toward a subject, typically a patient in a medical diagnostic application, and a portion of the radiation passes through the subject and impacts a detector. The surface of the detector converts the radiation to light photons, which are sensed. The detector is divided into an array of discrete picture elements or pixels, and encodes output signals based upon the quantity or intensity of the radiation impacting each pixel region. Because the radiation intensity is altered as the radiation passes through the subject, the images reconstructed based upon the output signals may provide a projection of tissues and other features similar to those available through conventional photographic film techniques.
In use, the signals generated at the pixel locations of the detector are sampled and digitized. The digital values are transmitted to processing circuitry where they are filtered, scaled, and further processed to produce the image data set. The data set may then be used to reconstruct the resulting image, and display the image.
A number of devices have been conceived to address the needs of portable radiography, including developments in portable units, detectors, and related digital imaging features. For example, U.S. Pat. No. 7,016,467 issued to Brooks discloses a mobile x-ray apparatus for generating a digital x-ray image and transmitting it to a remote site. The device includes a first computer, a flat panel detector in communication with the first computer, and an x-ray cart assembly removably supporting the first computer, which includes a cart with a battery charger and an x-ray machine in communication with the flat panel detector. It further includes an x-ray tube extendible from the cart, and a mechanism for framing a target body area of a patient.
U.S. Pat. No. 7,342,998 issued to Kump, et al., discloses an x-ray system quick-connect connection to allow an end-user to de-couple a portable x-ray detector from an x-ray scanner/host.
U.S. Pat. No. 743,428,470 issued to Koren discloses a mobile computed radiography unit. This system includes a scanner adapted to acquire one or more images from an image recording medium, a frame that supports the scanner, an x-ray source mounted to the frame, a transport mechanism coupled to the frame and adapted to facilitate transport of the mobile apparatus between locations, and a display coupled to the frame and connected to the scanner to display the images acquired by the scanner.
U.S. Pat. No. 7,783,008 issued to Jabri describes a technique for placing markers on digital radiographic images, such as projection x-ray and tomosynthesis images. A tag encoding data is disposed on or near a component of a radiographic imaging system, such as on a digital detector. The tag is read during an imaging session, and human readable indicia for the marker is generated that can be permanently included in the resulting images or displayed when desired, such as in an overlay.
U.S. Pat. No. 7,798,710 issued to Barnes disclosures a mobile radiographic unit with improved x-ray scatter control. Improved x-ray scatter control is provided through the alignment of the system with the focal line of an anti-scatter grid. In a preferred embodiment, the system comprises an x-ray source assembly, a tube housing mounting, a measuring system, a motion control system and a processor in communication with the measuring system and the motion control system. The system attempts to establish an optimal alignment, although it discloses no means for controlling or preventing the emission of radiation.
U.S. Pat. No. 7,817,040 issued to Homanfar, et al., discloses a radio frequency identification (RFID) system which detects conditions of alignment, wherein the system may be used with hand-held, fixed-in-place, stationary, and permanently mounted apparatus. An RF interrogator, an RF transponder, and an x-ray sensitive imaging device, and its holder are configured to be critically aligned to a dental x-ray machine head apparatus, rendering repeat imaging unnecessary. The x-ray emitter may be further configured to automatically obtain a desired x-ray image or configured so that the device cannot activate and provide a radiograph until alignment with the transponder and associated x-ray sensitive imaging device has occurred. A key limitation of this system is its reliance on RFID methods to determine orientation and location, because radio frequencies may interfere with other critical or life support equipment such as in an intensive care unit (ICU). There is also no mention of other methods to determine orientation and location, such as inertial measurement units (IMU's), or other features which would make this device suitable for use in the context of an ICU or neonatal ICU (NICU).
U.S. Pat. No. 7,947,960 issued to Wu, et al., discloses a portable detector panel including an x-ray detector assembly having an x-ray detecting surface on its surface, a box-like case that houses the x-ray detector assembly therein and whose upper part that is opposite to the x-ray detecting surface is x-ray transmissive.
U.S. Pat. No. 804,141,045 issued to Foos, et al., discloses a mobile digital radiography system including a mobile x-ray source; a mobile computer, the computer having a display for radiographic images and related information; and a digital radiography detector, the detector and x-ray source in communication with and under control of the computer. No alignment features are disclosed in this system, nor any functionality to control or prevent the emission of radiation based on alignment or location of the detector.
U.S. Publication No. 2002/015041415 invented by Barnes, et al., discloses a mobile radiographic unit with improved x-ray scatter control. Improved x-ray scatter control is provided through the alignment of the system with the focal line of an anti-scatter grid. The system comprises an x-ray source assembly, a tube housing mounting, an automatic measuring means, a motion control means and a processing means in communication with the automatic measuring system and the motion control system. Although, the alignment of the system occurs with minimal input by the operator, there is no means provided which controls or prevents the emission of the radiation source based on the alignment condition.
U.S. Publication No. 2008/014242837 invented by Heath, et al., discloses a position sensing apparatus for radiation imaging. The system includes a radiation head with a radiation source and an adjustable angular orientation. A radiation image detection device has a photostimulable medium (such as a detector) that records an image according to radiation emitted from the radiation source. A measurement sensor apparatus, preferably inertial, is coupled to the detector to provides three-dimensional data for determining the orientation of the photostimulable medium. There is at least one indicator responsive to the orientation data from the measurement sensor apparatus for indicating an orientation adjustment of the radiation source is needed in at least one direction. While this system attempts to establish orientation of the detector and radiation source, the system does not control or prevent the emission of radiation from the radiation source.
Despite the foregoing advances in the art, there remain significant shortcomings in existing systems used for diagnostic imaging. Current mobile radiography/fluoroscopic imaging systems are cumbersome and expensive. These mobile systems normally incorporate a fixed, mechanical C-Arm, or other mechanical configuration which connects the radiation source and the detector to one another, in order to mechanically fix the detector relative to the x-ray source to prevent misalignment outside of normally government-regulated, pre-determined tolerances. In addition, the spatial location of the detector is not always known relative to the x-ray source, as is the case in fixed, permanent digital radiography/fluoroscopic (DR) imaging systems. Especially when the subject to be imaged is very fragile or largely immobile, the need continues to exist for mobile systems which comply with applicable governmental regulations, while being easy and safe to use in a variety of settings.